Automatic Reasoning for Defining Lathe Operations for Mill-Turn Parts: A Tolerance Based Approach

With the increase in computer-controlled hybrid machining (e.g., mill-turn machining), one needs to discern what features of a part are created during turning (i.e., with a lathe cutter) versus those created by milling. Given a generic part, it is desirable to extract the turnable and nonturnable features in order to obtain feasible machining plans. A novel approach for automating this division and for defining the resulting turning operations in a hybrid process is proposed in this paper. Given a mill-turn part, the algorithm first identifies the dominant rotational-axis in order to quickly generate the axisymmetric “as-lathed” model. This model is then subtracted from the original part to isolate the nonturnable features. Next, the as-lathed model is translated to a label-rich graph, which is fed into a grammar reasoning algorithm to produce feasible turning sequences. During the turning process planning, the knowledge encapsulated in the design tolerances is used to guide the generation of feasible turning sequences. Two case studies are provided to explain the details of our algorithm. One of the suggested turning plans is compared with a manually proposed plan from an expert machinist and the results show the optimality of our plan in satisfying the prescribed tolerances.

Automatic Reasoning for Defining Lathe Operations for Mill-Turn Parts

With the increase in computer-controlled hybrid machining (e.g. mill-turn machines), one needs to discern what features of a part are created during turning (i.e. with a lathe cutter) versus those created by milling. Given a generic part shape, it is desirable to extract the turnable and non-turnable features in order to obtain feasible machining plans. A novel approach for automating this division and for defining the resulting turning operations in a hybrid process is proposed in this paper. The algorithm is based on identifying the dominant rotational-axis and performing several non-uniform lateral cross-sections to quickly generate the “as lathed” model. The part is then subtracted from the original model to isolate the non-turnable features. Next, resulting model and features are translated to a label rich graph and fed into a grammar reasoning tool to produce feasible manufacturing plans. The setup design is also studied against the tolerances specified by the designer. Performance of the algorithm has been tested on several examples ranging from simple to complex parts.

Analysis of Cutter Offset Function in NC Lathe and its Applications

The concept and usage of cutter offset compensation was introduced, and the cutter wear compensation and cutter radius compensation were calculated. The processing error produced by tool corner radius was analyzed, and the function, application occasion and usage of radius compensation in CNC lathe cutter is discussed, which has special significance for the accurate machining. The examples are given to illustrate how to using methods and skills in NC turning programming reasonably.